實(shí)踐中，單片機(jī)端口在連接開關(guān)器件時(shí)都要考慮消抖的問題，或在硬件上增加延遲，或是增加軟件延遲查詢的功能模塊。這里，我們考慮這樣一個(gè)檢測(cè)電路：?jiǎn)纹瑱C(jī)連接一個(gè)開關(guān)和兩個(gè)LED。程序是這樣的，如果開關(guān)的消抖正確，就點(diǎn)亮LED1，否則就閃亮LED2。按下開關(guān)，點(diǎn)亮LED1，釋放開關(guān)，LED1即熄滅。我們加入20毫秒的消抖延遲時(shí)間。當(dāng)檢測(cè)到開關(guān)為低電平時(shí)，單片機(jī)在延遲20毫秒后再次檢測(cè)開關(guān)的狀態(tài)。如果此時(shí)開關(guān)狀態(tài)為高，則LED2就閃亮，如為低則點(diǎn)亮LED1。

源代碼：

led1 bit P2.0
led2 bit P2.1
switch1 bit P1.0
ORG 0000h
setb switch1 //initialize switch 1 as input
setb led1 //Turn OFF LED1
setb led2 //Turn OFF LED2

wait:
jb switch1,wait // Wait till switch1 has been pressed
call debounce_delay
jb switch1,c1_wait
//switch low even after debouncing period
//switch has been succesfully debounced
clr led1 //Turn ON LED1
jnb switch1,$ //wait till switch has been released
setb led1 //Turn OFF LED1
ajmp wait

c1_wait:
//Switch PIN high after debounce period so error in debouncing
cpl led2
ajmp wait

debounce_delay: //Subroutine for generating 20ms delay
MOV r7,#245
l1_debounce_delay:
MOV r6,#40
djnz r6,$
djnz r7,l1_debounce_delay
ret

END